The present invention relates to a cooling device using air as a refrigerant.
In recent years, the degradation of the environment surrounding the earth due to flon gas, such as the ozone layer depletion and global warming, has become a serious problem. Therefore, there are trends toward environment-friendly cooling devices which do not use flon gas. As one of the trends, clean and safe cooling devices using natural air as a refrigerant have been under development.
A cooling device using air as a refrigerant typically takes in and compresses the outside air through a compressor, leads the compressed and heated air to a heat exchanger for cooling to about room temperature, and leads the air to an expander for adiabatic expansion. The temperature of the air is reduced to a low temperature on the order of minus ten degrees. The cold air is led to a freezing chamber to absorb heat from, and freeze, an object.
However, the cooling device as described above has the following problems in practice:
(1) The compressor and the expander are driven by separate driving systems. The device is uneconomical because the compressor requires an energy for compressing the outside air, and the expander requires an energy for expanding the compressed air, whereby the power consumption accumulates to increase the running cost.
(2) The cold air may have pulsation based on the operation phase of the expander. In order to constantly cool the object, it is desired to suppress such pulsation in the cold air.
(3) In the expander, the temperature of the air decreases rapidly to a temperature on the order of minus several ten (xc2x0 C.), whereby moisture contained in the air in the expander may lead to dew formation/icing onto the discharge valve, etc., of the expansion cylinder, thereby hampering the operation of the cooling device.
(4) It is desired to further improve the cooling efficiency and the energy efficiency during operation of the cooling device.
Thus, an object of the present invention is to provide a cooling device using air as a refrigerant which solves the above-described problems.
In order to achieve the above-described object, a cooling device of the present invention comprises: one or a plurality of compression, cylinders each accommodating therein a compression piston so as to allow reciprocating motion thereof; a plurality of expansion cylinders each accommodating therein an expansion piston so as to allow reciprocating motion thereof; one crank shaft or a plurality of crank shafts rotating in an interlocked manner; a first crank mechanism for coupling the compression pistons so as to allow reciprocating motion thereof from the crank shaft via a crank pin; a second crank mechanism for coupling the expansion pistons so as to allow reciprocating motion thereof from the crank shaft via a crank pin; a driving device for rotating the crank shaft; a compressed air supply passage for communicating a discharge port of each compression cylinder with an intake port of each expansion cylinder, the discharge port being provided for discharging a compressed air which is introduced through an intake port of the compression cylinder and compressed within the compression cylinder; a primary cooler provided along the compressed air supply passage; and a cold air discharge manifold for discharging the air whose temperature is reduced through adiabatic expansion within the respective expansion cylinders to the outside.
Means for reducing the pulsation of the cold air comprises: the plurality of expansion cylinders; one crank shaft or a plurality of crank shafts rotating in an interlocked manner with the same cycle; a second crank mechanism for coupling the respective expansion pistons so as to allow reciprocating motion thereof from the crank shaft via a crank pin with a predetermined phase difference with respect to one another; and a cold air discharge manifold for communicating together a plurality of discharge ports for discharging the air whose temperature is reduced through adiabatic expansion within the respective expansion cylinders to the outside.
Means for preventing the dew formation or icing within the expansion cylinder, etc., comprises an air drying device provided in an intake passage for introducing air into the intake port of the compression cylinder or in the compressed air supply passage.
In such a case, if the air drying device is provided upstream of the primary cooler along the compressed air supply passage, a secondary cooler is provided between the air drying device and the compression cylinder.
Means for improving the cooling efficiency and/or the energy efficiency during operation comprises, for example, an introduction pipe which is provided so as to introduce air from the cold air discharge space of the cold air discharge manifold into the intake port of the compression cylinder, and an introduction pipe which is provided so as to introduce a part of the air within the cold air discharge manifold into the compression cylinder.
In a cooling device of the present invention, a flywheel for ensuring a stable operation of the cooling device is provided for one of the crank shafts.
In a cooling device of the present invention, the adiabatic cylinder is formed by inner and outer tubes layered together, the inner tube being made of a stainless steel.
In a cooling device of the present invention, as means for improving the cooling efficiency and/or the energy efficiency during operation, each two of the cylinders are provided along the same cylinder axis line so as to oppose each other with respective cylinder heads thereof facing away from each other, the cooling device comprising: a piston rod for coupling together respective pistons of the both cylinders and linearly reciprocating along the cylinder axis line; and a crank mechanism comprising an inner periphery sun gear in which a central axis of a pitch circle thereof orthogonally crosses the cylinder axis line and which is fixedly provided in parallel to the cylinder axis line, a planetary gear having a pitch circle diameter which is one half of the pitch circle diameter of the inner periphery sun gear, the planetary gear being capable of rotating and revolving while meshing with the inner periphery sun gear, a crank shaft rotatably provided about the central axis of the pitch circle of the inner periphery sun gear, and an arm portion protruding in a radial direction of the crank shaft for rotatably supporting a rotation axis of the planetary gear, wherein an intermediate portion of the piston rod is pin-engaged along a circumference of the pitch circle of the planetary gear.
A cooling device of the present invention comprises: a cylinder unit comprising a compression cylinder accommodating therein a compression piston so as to allow reciprocating motion thereof and a plurality of expansion cylinders each accommodating therein an expansion piston so as to allow reciprocating motion thereof, the cylinders being provided along the same cylinder axis line with the respective cylinder heads thereof facing away from each other; a piston rod for coupling together the compression piston and the expansion pistons of the cylinder unit and linearly reciprocating along the axis line of the cylinder unit; a crank mechanism comprising an inner periphery sun gear in which a central axis of a pitch circle thereof orthogonally crosses the cylinder axis line between the cylinders of the cylinder unit and which is fixedly provided in parallel to the cylinder axis line, a planetary gear having a pitch circle diameter which is one half of the pitch circle diameter of the inner periphery sun gear, the planetary gear being capable of rotating and revolving while meshing with the inner periphery sun gear, a crank shaft rotatably provided about the central axis of the pitch circle of the inner periphery sun gear, and an arm portion protruding in a radial direction of the crank shaft for rotatably supporting a rotation axis of the planetary gear, wherein an intermediate portion of the piston rod is pin-engaged along a circumference of the pitch circle of the planetary gear; a driving device for rotating the crank shaft; a compressed air supply passage for communicating a discharge port of the compression cylinder with an intake port of each expansion cylinder, the discharge port being provided for discharging a compressed air which is introduced through an intake port of the compression cylinder and compressed within the compression cylinder; a primary cooler provided along the compressed air supply passage; and a cold air discharge manifold for communicating together discharge ports for discharging the air whose temperature is reduced through adiabatic expansion within the respective expansion cylinders to the outside.
A cooling device of the present invention may comprise a cam mechanism, wherein a cam follower is provided at a pin engagement section between the planetary gear and the piston rod, and a cam guide surface is set so that the planetary gear meshes with the sun gear on a front side with respect to a rotation direction thereof before the expansion piston reaches a top dead center. The cam mechanism may have a cam guide surface which is set so that the planetary gear meshes with the sun gear on a front side with respect to a rotation direction thereof before the expansion piston reaches a bottom dead center.
A cooling device of the present invention comprises: a compression cylinder unit in which two compression cylinders each accommodating therein a compression piston so as to allow reciprocating motion thereof are provided along the same cylinder axis line with respective cylinder heads thereof facing away from each other; an expansion cylinder unit in which two expansion cylinders each accommodating therein a expansion piston so as to allow reciprocating motion thereof are provided along the same cylinder axis line with respective cylinder heads thereof facing away from each other; a plurality of piston rods provided respectively for the cylinder units, each piston rod coupling together the two pistons of each cylinder unit and linearly reciprocating along the axis line of the cylinder unit; a crank mechanism comprising an inner periphery sun gear in which a central axis of a pitch circle thereof orthogonally crosses the cylinder axis line between the cylinders of each cylinder unit and which is fixedly provided in parallel to the cylinder axis line, a planetary gear having a pitch circle diameter which is one half of the pitch circle diameter of the inner periphery sun gear, the planetary gear being capable of rotating and revolving while meshing with the inner periphery sun gear, a crank shaft rotatably provided about the central axis of the pitch circle of the inner periphery sun gear, and an arm portion protruding in a radial direction of the crank shaft for rotatably supporting a rotation axis of the planetary gear, wherein an intermediate portion of the piston rod is pin-engaged along a circumference of the pitch circle of the planetary gear; power transmission means for interlocking the crank shafts provided in the respective cylinder units with each other; a driving device for rotating the crank shaft; a compressed air supply passage for communicating a discharge port of each compression cylinder with an intake port of each expansion cylinder, the discharge port being provided for discharging a compressed air which is introduced through an intake port of the compression cylinder and compressed within the compression cylinder; a primary cooler provided along the compressed air supply passage; and a cold air discharge manifold for communicating together discharge ports for discharging the air whose temperature is reduced through adiabatic expansion within the respective expansion cylinders to the outside.
In a cooling device of the present invention, a compressed air is supplied into the compressed air supply passage, the compressed air being produced by a pressurizing compressor which can be operated as necessary. In such a case, the device may further comprise a depressurizing device provided along the compressed air supply passage, and a temperature sensor for measuring the temperature of the produced cold air, so that the pressure of the air within the compressed air supply passage is increased and decreased based on the temperature sensor so as to obtain a cold air of a desired temperature.